1. Field
The present invention relates generally to data communication, and more specifically to a “High-level Data Link Control” (HDLC) hardware accelerator for framing and deframing PPP packets.
2. Background
The explosive growth of computer networks, such as the Internet, has spawned demands for high data rate infrastructures that can support the enormous amount of data traffic generated by these networks. Approximately concurrent with the growth of the Internet is the deployment and acceptance of wireless communication systems capable of supporting a variety of services. Newer-generation wireless communication systems are designed to efficiently provide data and voice communication, including data traffic generated by the Internet.
A data communication between a client and a server is typically achieved via a number of communication and network elements. For example, to remotely access a server over a wireless link, a terminal may communicate via the wireless link with an access point, which may further communicate with the server via routers, hubs, bridges, and so on. These elements communicate with each other via specific protocols that may be defined based on an open model or a proprietary model.
Standard Internet data communication is typically supported via a Transmission Control Protocol (TCP) layer that operates on top of an Internet Protocol (IP) layer, which may further operate on top of a Point-to-Point Protocol (PPP) layer. These layers are defined by the Open Systems Interconnection Reference Model, which is commonly referred to as the OSI model and is well known in the art. Wireless communication may be supported via a Radio Link Protocol (RLP) layer that operates on top of a physical layer such as, for example, a high data rate (HDR) layer defined by IS-856.
Wireless communication devices may thus be required to support PPP for packet data communication and RLP for wireless communication. Each protocol layer specifically defines the format for that protocol's transmission unit, which is a “packet” for the RLP layer and a “frame” for the PPP layer. Each PPP frame is typically generated by encapsulating a PPP packet.
Conventionally, the processing of RLP packets to recover PPP packet data and the processing of RLP packet data to form PPP packets are performed by software executed on a processor. To recover the PPP packet data in each RLP packet, the software typically needs to retrieve each byte of the RLP packet, determine whether any processing needs to be performed on the byte, and then perform the necessary processing (if any). The “conversion” of data between PPP and RLP can consume a large percentage of the processing capability of the processor. This would then necessitate a faster processor for the wireless communication device and/or limit the functions and features that may be provided by the device. Moreover, additional memory is typically required to perform the conversion in software.
There is therefore a need in the art for a hardware accelerator that can recover PPP packet data from RLP packets and form PPP packets from RLP packet data.